According to The Inquirer it's possible that AMD's Socket AM2 processor support DDR2 memory.
That is the 2007 architecture but we spoke with a few people that believe that DDR 3 specification is so close to DDR 2 that it might just work. It is technically possible, it should be.
AMD or the motherboard manufacturers should do some BIOS tweaks to make it happen but the bottom line is that it could be done.
There is a big indication that DDR 3 ram modules might be identical to DDR 2 ones. So there is a big chance that you will be able to plug the new memory in the old slots.
However, it's possible that a new chipset revision or a Socket AM2 tweak or re-spin is necessary to make the support.